The Warm Arctic workshop was held at DMI on the 5th and 6th December with several invited guest speakers from outside the ice2ice group. Svend Funder and Kurt Kjær from the Centre for Geogenetics at the Natural History Museum of Denmark in Copenhagen gave a good introductory overview of the current state of the art in terms of paleoproxies for Arctic sea ice extent and ice sheet extent in Greenland respectively. This was excellent framing for the remainder of the workshop.
Sea ice processes are not straight forward. credit Vihma
Timo Vihma from the Finnish Meteorological Institute contributed an interesting talk on connections between the Arctic and the mid-latitudes including a very comprehensive diagram showing important processes and linkages, while on the second day, external speakers Wieslaw Maslowski and Dirk Notz (remotely) gave a nice overview of the state of the sea ice modelling from their respective groups, leading to an intense discussion on whether the ocean or the atmosphere was the dominant driver of change in the Arctic. Dirk Notz work shows nicely that sea ice decline follows emissions pretty directly. Internal speakers from DMI, included Rasmus Tonboe who gave a good overview of current sea ice data available from EUMETSAT and Torben Schmidt handled the modelling side with a look at multidecadal variability in the Arctic ocean.
Notz talked about the effect of global CO2 on sea ice
Various ice2ice members also gave talks on different aspects of the project including a presentation by Shuting Yang on the Arctic sea ice loss and Northern hemisphere winters. There was a very comprehensive discussion by Peter Langen on Greenland ice sheet surface mass balance, some early work from Martin Stendel on the Arctic seesaw when there is little or no sea ice and PI Jens Hesselbjerg Christensen on the state of sea ice in a 1.5C world (spoiler: there won’t be very much). Rasmus Anker Pedersen also showed some of his work on the atmospheric response to a sea ice free Arctic.
credit Svend Funder
As the aim of the workshop was to produce a review paper on the subject, there were two wide ranging discussion sessions where a very wide range of related topics were explored, including the aforementioned question of the relative importance of ocean and atmosphere and how the processes and feedbacks between the two might look. There was also much discussion on ways to improve sea ice representations in models and the importance of both including more comprehensive processes and improved model resolution in both ocean and atmosphere models. Finally, the workshop participants structured these issue into a format to create both a publication and potentially a conference session in the future, watch this space!
The workshop was organized by Christian Rodehacke, Peter Langen, Shuting Yang and Jens Hesselbjerg and was held at DMI.
The ICAT PhD school was held from Monday 31/10 to Saturday 5/11/16. The Ice Core Analysis and Techniques (ICAT) PhD school supported by ice2ice and hosted over 30 students from 13 countries at CIC in Copenhagen. Through a mixture of hands on exercises in the three ice core laboratories, a mixture of lectures all related to ice cores, and several social events to enhance colaborations between students, the students learned all there is to know about ice cores. With student responses like “It was an awesome experience”, “congratulations on a great course-I am very thankful” and “This was a phenomenal PhD course” we hope to secure enough funding to be able to run it again next year.
The ICAT PhD’s in the limestone quarry at Faxe
The ICAT PhD school was run for the first time this last week (31/10-5/11). The course was intended to increase the knowledge on ice core analysis techniques (ICAT) and people from more than 13 countries participated. The students had a diverse background; most were already familiar with ice cores, working on a particular proxy from ice cores, but also a few ice sheet modellers, climate modellers and people working with other paleo-archives attended, among these were 4 ice2ice participants.
Lots of discussion and collaboration between the students in the breaks.
All days started with 5 minute presentations by students. It was great to see the diversity of the students and this way the newest research within ice core science was well represented. A number of Centre for Ice and Climate’s own scientists continued with lectures covering ice core history, water isotopes, Continuous flow analysis techniques, gas extraction and analysis, ice core drilling, dating of ice cores, borehole measurements, multi core variability, statistics and trends, water isotope modelling, ice sheet flow and comparison to other paleo-archives. Furthermore, the invited speakers Professor Joe McConnell, from the Desert Research Institute, Nevada talked about his research in Anthropocene contaminants as observed in ice cores measured by continuous flow analysis and professor Edward Brook, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University gave lectures about the extraction of greenhouse gases and the changes of them as observed in ice cores.
Sune Rasmussen stressing correct (danish) pronunciation of important climate events like Allerød and Bølling.
Lead investigator for ice2ice at DMI Jens Hesselbjerg taught the students about climate modelling and how to compare ice cores to models and Helle Sørensen from the math department at the University of Copenhagen introduced basic statistics of time series.
Exercises and laboratory visits were a great opportunity to get hands on experience with real data
Two of the days the students got hands-on experience by working in the laboratories; ice2ice PhD Niccolo Maffezoli showed the IC laboratory, where discrete ice samples are analyzed for ions. Professor Thomas Blunier ran an exercise in the gas laboratory where the students breath was analysed similar to ice core samples on a methane Picarro analyser, in the water isotope laboratory postdoc Vasileios Gkinis analysed students own water samples to reproduce the meteoric water line and in the CFA laboratory Marius Simonsen and Helle Kjær had the students prepare and run standards for ammonium. Further the student got hands on experience in annual layer counting led by specialist Mai Winstrup and simple Herron-Langway modelling led by Paul Vallelonga.
Students busy in the Faxe quarry looking for 64 million year old fossils of the corals that used to be.
To increase the interaction amongst students an excursion to the UNESCO site of Stevns Klint took place in the middle of the week. Stevns Klint is the best place in the world to see the fish clay layer from the extinction 65 million years ago. Also the excursion brought us to Geomuseum Faxe, and Faxe limestone quarry where students retrieved their own 63 million years old fossils. The excursion ended as the best excursions do with beer at a brewery.
The week ended with an official dinner and a few talks.
The course was organised by ice2ice postdoc Helle Astrid Kjær and Assoc. Professor Paul Vallelonga. This year we unfortunately did not have room for all that applied, so we hope to repeat the course next year.
Ice2Ice members from Centre for Ice and Climate recently published an article in the Nature-affiliated journal Scientific Reports titled “Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core”. Here you can read the corresponding author Paul Vallelonga’s explanation of the key findings in this new article.
Arctic sea ice: have we reached a climate threshold?
There are two kinds of sea ice in the Arctic – new, thin, sea ice that grows in the winter and melts in the summer (called seasonal or first-year sea ice); and older, thicker, sea ice that survives through the summer and continues to grow each winter (called multi-year sea ice). In the Arctic Ocean there is a central patch of multi-year sea ice, around which the seasonal sea ice grows in the winter and then breaks up and melts in the summer every year. When satellite measurements began in the 1970’s, the amount of old multi-year sea ice was 6 million km2, with more (9 million km2) seasonal sea ice growing around it each year. In the last decade, the amount of old multi-year sea ice has decreased – in 2016 it was 4 million km2 – which means that during the summer, less of the Arctic is covered by sea ice; and during the winter more of the sea ice is thin seasonal sea ice. There is an overall shift toward less Arctic sea ice throughout the year, and a greater proportion of that sea ice being the thin seasonal type.
Figure 1 – Arctic sea ice minima and maxima. These are two images of Arctic sea ice extent showing the maximum (left) and minimum (right) in 2015. The left image shows the combination of seasonal and multi-year sea ice, while the image on the right shows only the multi-year sea ice left at the end of summer. The pink lines show the 1980-2010 median sea ice extent maxima and minima. From nsidc.org.
Is the sea ice decrease since the 1970’s normal or extreme? Are these recent changes within the range of natural variability or has the Arctic system crossed some kind of natural threshold? The only way we can know the answer is by measuring how much Arctic sea ice there was in the past. This new study of ice cores published in the Nature-affiliated journal Scientific Reports takes us closer to finding out – giving us a measure of how much Arctic sea ice there was during three key time intervals: 1) 20 thousand years ago during the last ice age – when Greenland temperatures were about 20° colder; 2) 8 thousand years ago when Greenland temperatures were 2° warmer, known as the early-Holocene period; and 3) during the last 3 thousand years of “normal” Arctic climate.
How to reconstruct sea ice from Greenland ice cores?
The key advance here is the use of a chemical marker called bromine, which we have been able to link to seasonal sea ice. Bromine is present in seawater in small amounts – for every kilogram of seawater there are about 11 grams of sodium but just 7 milligrams of bromine – a thousand times less bromine than sodium. The ratio of bromine to sodium in seawater is the same in all oceans, but we have found that seasonal sea ice concentrates bromine much more than sodium. This bromine concentration enrichment is due to two processes:
Firstly the process of making seasonal sea ice concentrates sea salts (including bromine) into surface crystals (frost flowers) and salty brine channels, which are able to react with the atmosphere. This rich salty soup is only present in seasonal sea ice because the multi-year sea ice doesn’t contain brine or host surface salt crystals.
The second ingredient is sunlight. In March and April, Arctic springtime begins with sunlight appearing over the horizon and illuminating freshly-formed seasonal sea ice. The sunlight activates many photochemical reactions; one of the most important is the break-up of bromine gas (Br2) released from the seasonal sea ice surface. When bromine gas splits into two bromine radicals, the radicals start new reactions in the sea ice which lead to the production of more bromine gas. This chain reaction is called a bromine explosion, resulting in an enhanced concentration of bromine in the atmosphere above seasonal sea ice in the Arctic.
In a previous study (Spolaor et al., 2014) we looked at snow and ice in Greenland (at the NEEM ice core drilling site) and Antarctica (from a near-coastal site in East Antarctica called Law Dome) and found a regular spring/summer bromine enrichment peak, matching the seasonal pattern expected from chemical theory and satellite measurements. Bromine was measured in the NEEM ice core using an Inductively Coupled Plasma Mass Spectrometer (ICPMS) instrument located at the University Ca’ Foscari in Venice. The ICPMS is able to separate bromine from other elements such as sodium, and measure their concentrations very precisely. It took about two months to measure the 350 ice core samples from the NEEM ice core.
Figure 2 – Bromine enrichment and transport. Bromine originates from the ocean surface, but is concentrated by sunlight-driven chemical reactions occurring above seasonal sea ice. The enriched bromine is transported over the Greenland ice sheet and deposited onto the snow surface.
What have we found?
We have looked at three different climate periods to interpret the NEEM ice core data:
The coldest part of the ice age, 20 thousand years ago when Greenland was 20°C colder than today.
The warmest part of the Holocene, 8 thousand years ago when Greenland was 2°C warmer than today.
The “recent” period in Greenland covering the last 3 thousand years.
We’ve found that the average bromine enrichment – indicating the amount of seasonal sea ice – over the last 3 thousand years is more than the glacial but less than the warm early-Holocene period 8 thousand years ago. This suggests that the amount of seasonal sea ice during the last 3 thousand years is lower on average than it was 8 thousand years ago, just after the end of the last ice age. The results also indicate that multi-year sea ice will continue to decline into the future as the Arctic warms.
So we cannot yet answer the question “have we reached a climate threshold?” but we do know there was less multi-year sea ice 8 thousand years ago, when Greenland climate was just 2°C warmer, compared to the situation over the last 3 thousand years. This research sets up a whole range of new questions to ask:
How do the sea ice changes over the last 30 years compare to the last 3 thousand years?
What is the bromine record like at other places in Greenland?
What can bromine tell us about sea ice during the Eemian warm climate period before the last ice age, when Greenland temperatures were at least 5°C warmer than today?
Figure 3 – Reconstructing past seasonal sea ice from bromine in ice cores. The graph shows the three climate scenarios studied. During the last ice age there was no seasonal sea ice because the oceans were completely covered by multi-year sea ice. The bromine-to-sodium ratios measured in the NEEM ice core are lower over the last 3 thousand years than in the warmest part of the Holocene 8 thousand years ago, indicating that there was more seasonal sea ice 8 thousand years ago compared to the last 3 thousand years.
Where to next?
In the future we plan to expand the published study in two ways – we want to study in more detail the sea ice changes that occurred during the last ice age; and we want to compare the NEEM results to other locations in Greenland. From the published NEEM bromine record, we see that sea ice also changed during the last ice age, particularly during the rapid warming events known as Dansgaard-Oeschger events. Investigating sea ice changes during the glacial is a key goal of the ice2ice project. Also, we are keen to produce sea ice records from bromine measured in East Greenland ice cores, such as Renland and EastGRIP. These ice cores collect sea salts from the Nordic Seas and allow us to study sea ice changes in a different part of the Arctic Ocean. This will tell us more about how sea ice has changed in the Arctic and the role that Atlantic Ocean circulation changes might play in building or destroying sea ice in the Arctic. These newer ice cores will also allow us to collect bromine measurements covering the last 30 years to compare with the satellite observations of sea ice.
Spolaor, A. et al. Canadian Arctic sea ice reconstructed from bromine in the Greenland NEEM ice core. Scientific Reports6, 33925 (2016) doi: 10.1038/srep33925. http://www.nature.com/articles/srep33925
Simpson, W. R. et al. Halogens and their role in polar boundary-layer ozone depletion. Atmos. Chem. Phys.7, 4375-4418 (2007) doi: 10.5194/acp-7-4375-2007. http://www.atmos-chem-phys.net/7/4375/2007/
A scenic view of the one-masted boat “Väderöjulle” and the head of the Gullmar fjord.
Once each year the historic hydrographic station on Bornö sets the stage for the NBI/UH summer school on ocean physics. Bornö, a small rock island with dense vegetation, is beautifully located close to the head of the 25km long Gullmar Fjord on the west coast of Sweden, a couple of hours by car to the north of Göteborg. This year’s topic was ocean small-scale turbulence, and besides the delegation from Centre for Ice and Climate, PhD students, postdocs and faculty from University of Hamburg (UH) and Leibniz Institute of Baltic Sea Research Warnemünde (IOW) participated as well.
Approaching the hydrographic station by boat.
Gullmar fjord has previously been subject to an intense study of its pronounced seiche motion, a standing wave in a closed or semi-closed basin, and the effect of this phenomenon on the turbulent mixing of the dense deep- and bottom water, which is stagnant during the summer months of the year. In perfect alignment with this year’s topic, existing literature on the fjord dynamics was presented during the morning sessions by the PhD students. These presentations was followed by lectures on the fundamentals of ocean small-scale turbulence and fjord physics.
Hans Burchard from IOW giving a lecture on Baltic Sea dynamics.
The lectures and presentations were accompanied with measurement sessions carried out during the afternoons. Various instruments were lowered from the hanging bridge at the hydrographic station to examine the properties of the water column. Of greatest interest was the microstructure profiler, brought by Lars Umlauf from IOW, which measures small-scale variations in the velocity shear that can be used to infer dissipation rates, a measure of the degree of turbulence. No less than 200 microstructure profiles were obtained during the week and provided a glimpse into the evolution of the fjord during the summer school.
Mads (CIC) and Philipp (UH) carry the CTD to the hanging bridge.
One special member of the school cannot go unmentioned, the one-masted boat “Väderöjulle”. In the late hours of the afternoon when reflection had to be made upon the turbulent thoughts that developed during the day, she provided an excellent opportunity to get a better view on the fjord and learn how to sail.
Lars Umlauf (IOW) holds the microstructure profiler while Xaver (IOW) cleans it.
Please see Søren’s website (http://www.gfy.ku.dk/~hpn661/) for further information on past and the present summer school at Bornö, as well as additional photographs and results from our measurement campaign.
A break on the warm cliffs. From left to right: Søren (CIC), Xaver (IOW), Mads (CIC) and Selina (IOW).
The 8th Advanced Climate Dynamics Courses – ACDC summer school took place from 8th to 19th August 2016 in Norris Point, Newfoundland. The topic of this year’s ACDC was understanding the basic principles and dynamics behind centennial to millennial scale climate variability and their link to past, present and future changes to high latitude climate.
ACDC 2016 group picture on Tablelands. Photo by Ryan Love.
Fun in the sunset light on the top of Tablelands mountain plateau. Photo by Ryan Love.
27 European, Canadian and US-based master, PhD students and PostDocs joined lectures of climate science with both fundamental lectures on core topics and topical lectures in the two weeks. The diverse background of the students and lecturers reflected the interdisciplinary nature of topics, combining all fields from atmosphere, oceanography, glaciology to geology, from proxy analysis to climate modelling. The course was well structured with both lectures, discussions, field trips and group projects. We ended the summer school by presented the group projects to the class, which topics were all from ice modelling, ocean modelling, lake sediments and icebergs.
Coring sediment cores from a small lake in Gros Morne National Park. Photo by Marie KapschBonfire on the beach. Photo by Iben Koldtoft.
The school was based at Bonne Bay Marine Station in Gros Morne National Park, which provided a unique location for field excursions and sightseeing. During our stay we therefore visited several locations to study the local climate, glaciological and geological history. Especially the hike during the weekend to Tablelands, a mountain plateau on the other side of the bay, was a really informative and fun field trip.
Hiking on the top of Tablelands. Photo by Kerim NisanciogluEnjoying the view during a break in the glacier formed valley. Photo by Benoit Lecavalier
In the two weeks the weather was unbelievably good, which provided great conditions for being outside exploring the area by hiking, kayaking and bonfire on the beach.
Several people involved in the ice2ice project were presented at the summer school, namely Kerim Nisancioglu (Professor UiB), Jonathan Rheinlænder (PhD student UiB), Andreas Plach (PhD student UiB), Nadine Steiger (MSc UiB), Søren Borg Nielsen (PhD student UCPH) and Iben Koldtoft (PhD student DMI and UCPH).
Ice2Ice people on the way to Tablelands with the local boat. Photo by Kerim Nisancioglu.
We strongly recommend this summer school to all our colleagues working within the fields of climate science.
Want to see more pictures from the 2 weeks? Search for the #acdcsummerschool on both Instagram, Facebook and Twitter.
Written on behalf of the ice2ice PhD students by Iben Koldtoft.
These days the ship G.O. Sars is carrying ice2ice scientist with the goal of retrieving sediment cores to help answer the overall question of ice2ice: How does the sea ice effect land ice and vice verse?
G. O. Sars ready for departure from Reykjavik
Yesterday (16th Aug) the Calypso deep corer was installed in the ship and this morning (17th of August) it was tested. In the afternoon, the ship left Reykjavik and in the next few days shell scrape/dredging in the local area (10, 50 and 90 km from Reykjavik) will be performed. The ship will then proceed toward South-East Greenland. There it will dock at Narsarsuaq, while on the way marine coring for more sediment cores to investigate especially the sea ice variability and ocean current changes of the past.
The approximate journey of G.O. Sars ice2ice cruise 2016
Below a video of G.O. Sars from last years cruise:
The cruise is driven UiB and the Bjerkness center, but making for truly interdisciplinary reserach, 3 Niels Bohr Institute scientist normally working with ice cores and one DMI scientist who normally does climate modelling are also on board to learn about the sediment archive first hand.
Congratulations to Anne-Katrine Faber who succesfully defended her PhD thesis at Centre for Ice and Climate on June 02, 2016 and obtained the degree of Doctor of Philosophy. Anne-Katrine has in her PhD project worked on model-data comparison with Greenland ice core data and climate model results. As part of her project she has collaborated with climate modelers from USA and spent half a year as a visiting scientist at University of Colorado, Boulder. Furthermore during her PhD she participated in field work measuring isotopes in water vapour in the fjords of Greenland on board the ship ”Activ”. The thesis was titled Isotopes in Greenland precipitation: Isotope-enabled AGCM modelling and a new Greenland.
Rasmus-PhD
Congratulations to Ramus Pedersen who successfully defended his PhD thesis at Centre for Ice and Climate on June 12, 2016 and obtained the degree of Doctor of Philosophy. Rasmus was co-supervised from DMI. Rasmus has invesitigated if past warm climate states could potentially provide information on future global warming and also explored the atmospheric sensitivity to the location of sea ice loss. He found that the changes in the Arctic sea ice cover are important for shaping both past and future warm climate states. Nonetheless, the last interglacial is not an ideal analogue for future climate changes, as the changed insolation has a large impact – especially on the Greenland ice sheet. The thesis was titled Modelling interglacial climate – investigating the mechanisms of a warming climate.
Rasmus has been hired as a postdoc starting 1.8.2016. The two year position is part of the ice flow modelling team at CIC. Rasmus is a familiar face within ice2ice as he did his PhD on «Modelling interglacial climate – investigating the mechanisms of a warming climate» at DMI one of the partner institutions of ice2ice. During his PhD he amongst other climate effects studied the effect of losing sea ice.
Joel Pedro
Joel has been also been hired as a postdoc at CIC and started 1st of June. Joel has already been closely connected with the ice2ice community and was part of organizing the MIS3 workshop in 2014. Joel will continue his work comparing the timing and response to climate change using multiple paleo records.
The first set of ice2ice scientists arrived on the Greenland Ice Sheet last week and are now busy working from the EastGRIP camp.
After transferring through Kangerlussuaq, where we spent a few days packing pallets for the Hercules and making sure all our personal equipment was in order, we flew with the Air National Guard to EastGRIP. The science camp is situated in the northeastern corner of the ice sheet, on one of the fastest flowing ice streams in Greenland, responsible for ~18% of the total drainage.
Saying goodby to Eliza who will be the Field Operations Manager (FOM) at KangerlussuaqThe new team ready to depart Kangerlussuaq with the Air National Guard Hercules (LC130) to EastGRIPThe new team ready to depart Kangerlussuaq with the Air National Guard Hercules (LC130) to EastGRIP.The June EastGRIP crew in front of the dome!Main street in campIben on arrival EastGRIPKerim happy to find his flag at EastGRIPHelen’s first steps on the Greenland ice sheet.
In camp we were greeted by a happy gang of scientist, technical staff and a cook, all from different corners of the world. On the first day after arrival everyone was fully engaged in daily camp duties as well as setting up all the scientific equipment and experiments.
Iben and Helen celebrating completion of the foundations of the drill trench with Trevor and DennisThe Underhills of EastGRIP and the entrance to the extensive underground science and drilling trenchesHans-Christian explaining the water vapor tent lab to NiccoloHelen preparing the water vapor tower.View from camp toiletIben found the 2012 melt layer in the bottom of the new camp toilet hole
Highlights so far include erecting a mast to measure turbulent fluxes of oxygen isotopes, sampling surface snow and measuring accumulation, preparing the ski way for planes, building the foundations for the deep ice core drill and digging a new toilet (reaching as far down as the 2012 melt layer!).
Niccolo and Kerim drilling the shallow core from a 2m snow pitAnders and Iben ready to receive the drill containing the first ice core section from NiccoloNiccolo getting ready to drill a new shallow ice core in campIben and Helen getting ready to sample snowIntroducing Norwegian skis for efficient snow sampling at EastGRIPKerim out marking the 1km snow transect for samplingIben sampling at 1cm and 6cm for measurements of water isotopes
During the next days we will traverse to the edge of the ice stream to drill a few short cores as well as start on the main EastGRIP core (expected to reach 100m this season) at the location of the camp. Everyone is looking forward to many days of exiting science and fun on the ice!
